NumberofIntersectedRectangles

import java.util.Set;

public class NumberofIntersectedRectangles {
	 public class Solution {
	        private boolean intersect(int[][] r1, int[][] r2) {
	            return r1[0][0] < r2[0][0] && r1[0][1] < r2[0][1] && r2[0][0] < r1[1][0] && r2[0][1] < r1[1][1] ||
	                    r1[0][0] < r2[1][0] && r1[0][1] < r2[1][1] && r2[1][0] < r1[1][0] && r2[1][1] < r1[1][1];
	        }

	        private int find(int val, int[] parents) {
	            while (parents[val] != val) {
	                val = parents[val];
	            }
	            return val;
	        }

	        public int countIntersection(int[][][] rectangles) {
	            if (rectangles == null || rectangles.length == 0) return 0;
	            int n = rectangles.length;
	            int[] parents = new int[n];
	            for (int i = 0; i < n; i++) {
	                parents[i] = i;
	            }
	            for (int i = 0; i < n - 1; i++) {
	                for (int j = i + 1; j < n; j++) {
	                    if (intersect(rectangles[i], rectangles[j])) {
	                        int root1 = find(i, parents);
	                        int root2 = find(j, parents);

	                        if (root1 != root2) {
	                            parents[root1] = root2;
	                        }
	                    }
	                }
	            }

	            Set<Integer> set = new HashSet<>();
	            for (int i = 0; i < n; i++) {
	                set.add(find(i, parents));
	            }

	            return set.size();
	        }
	    }
}